来自其他活动的单选按钮仍然为空?

Question

在一个活动中，我有我的单选按钮。我能够在整个应用程序中保存单选按钮的选定状态。在另一个活动中，我想检查选中了哪个单选按钮，但单选按钮一直返回 null。

这是第一个活动：

sharedPreferences = getApplicationContext().getSharedPreferences(GetInfo, MODE_PRIVATE);

go_back_btn = (Button) findViewById(R.id.go_back_btn);
distancebtn_group = findViewById(R.id.distance_btn_group);
miles_btn = (RadioButton) findViewById(R.id.miles_btn);
kilometer_btn = (RadioButton) findViewById(R.id.kilometer_btn);

go_back_btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
sharedPreferences = getApplicationContext().getSharedPreferences(GetInfo, MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putBoolean(MILESBTN, miles_btn.isChecked());
editor.putBoolean(KMBTN, kilometer_btn.isChecked());
editor.apply();
Intent intent = new Intent(settings.this, home.class);
intent.putExtra(MILESBTN, miles_btn.isChecked());
intent.putExtra(KMBTN, kilometer_btn.isChecked());
startActivity(intent);
}
});
kilometer_btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
sharedPreferences = getApplicationContext().getSharedPreferences(GetInfo, MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putBoolean(KMBTN, kilometer_btn.isChecked());
editor.apply();

}
});
miles_btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
sharedPreferences = getApplicationContext().getSharedPreferences(GetInfo, MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putBoolean(MILESBTN, miles_btn.isChecked());
editor.apply();
}
});

sharedPreferences = getApplicationContext().getSharedPreferences(GetInfo, MODE_PRIVATE);
kilometer_btn.setChecked(sharedPreferences.getBoolean("kilometer_btn", true));
miles_btn.setChecked(sharedPreferences.getBoolean("miles_btn", false));

}

这是我的第二个活动：

distance_counter = (TextView) findViewById(R.id.distance_counter);
distancebtn_group = (RadioGroup) findViewById(R.id.distance_btn_group);
miles_btn = (RadioButton) findViewById(R.id.miles_btn);
kilometer_btn = (RadioButton) findViewById(R.id.kilometer_btn);
distancebtn_group = findViewById(R.id.distance_btn_group);


final SharedPreferences sharedPreferences = getApplicationContext().getSharedPreferences(settings.GetInfo, MODE_PRIVATE);
final Boolean milesbutton = sharedPreferences.getBoolean(MILESBTN, false);
final Boolean kilometerbutton = sharedPreferences.getBoolean(KMBTN, true);
Boolean milesbtn = getIntent().getBooleanExtra(MILESBTN, false);
Boolean kilometerbtn = getIntent().getBooleanExtra(KMBTN, true);
getIntent().getBooleanExtra(MILESBTN, false);
getIntent().getBooleanExtra(KMBTN, true);

}
}
});
}

@Override
public void onLocationChanged(Location location) {
curr_location = location;
if (start_location == null) {
start_location = curr_location;
end_location = curr_location;
} else
end_location = curr_location;

ChooseMetricUnits();
distance_counter.setText(new DecimalFormat("#.##").format(distance));
current_speed = location.getSpeed() * 2.236936;
SpdInmph.setText(new DecimalFormat("0.00").format(current_speed));
current_speed = location.getSpeed() * 3.6;
SpdInkmh.setText(new DecimalFormat("0.00").format(current_speed));
}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
}

@Override
public void onProviderDisabled(String provider) {
}

private void distanceInMeters() {
distance = distance + (start_location.distanceTo(end_location));
start_location = end_location;
}
private void distanceInMiles() {
distance = distance + (start_location.distanceTo(end_location) * 0.00062137);

}
private void distanceInkilometers() {
distance = distance + (start_location.distanceTo(end_location) / 1000);
start_location = end_location;

}


public void ChooseMetricUnits() {
final SharedPreferences sharedPreferences = getApplicationContext().getSharedPreferences(settings.GetInfo, MODE_PRIVATE);
Boolean milesbutton = sharedPreferences.getBoolean(MILESBTN, false);
Boolean kilometerbutton = sharedPreferences.getBoolean(KMBTN, true);
Boolean milesbtn = getIntent().getBooleanExtra(MILESBTN, true);
Boolean kilometerbtn = getIntent().getBooleanExtra(KMBTN, true);
getIntent().getBooleanExtra(MILESBTN, false);
getIntent().getBooleanExtra(KMBTN, true);
if(miles_btn.equals(milesbutton)) {
distanceInMiles();

：跑

java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.Object.equals(java.lang.Object)' on a null object reference
at mobile.run_interface.ChooseMetricUnits(run_interface.java:325)

在此处输入图像描述

如您所见，问题就在这里：

if(miles_btn.equals(milesbutton)) {

我已经使用了putBoolean和putExtra，看看当我从任何一个中提取值时是否会发生不同的事情。相同的结果。我已经将用于检索值的代码放在 create AND 下，也放在我的 ChooseMetricsUnits void 方法下。我的按钮仍然为空。

我做错了什么？

Answer 1

活动是否具有相同的布局？如果它们不同，请检查导入R.id.miles_btn

这里还有另一个问题：

if(miles_btn.equals(milesbutton)) 

miles_btn是单选按钮，milesbutton 是布尔值，因此您必须通过以下方式更改代码：

if(miles_btn.isChecked() == milesbutton) 

Answer 2

解决了这个问题：

希望这对将来的其他人有所帮助...\

private void ChooseMetricUnits() {
final SharedPreferences sharedPreferences = getApplicationContext().getSharedPreferences(GetInfo, MODE_PRIVATE);
final Boolean MetricUnit = sharedPreferences.getBoolean(settings.KMBTN, true);
if(MetricUnit) {
distanceInkilometers();
} else
distanceInMiles();
}
}